don't crash when building without baloo

show_information_panel is only created when building with baloo. only
access it when built with baloo, otherwise always report the panel as
off.

this fixes a nullptr deref because action() would return a nullptr since
show_information_panel isn't a thing in all build configurations

(full disclosure: I can't reproduce the crash, nor did I build without
baloo)

BUG: 431730

src/dolphinmainwindow.cpp

@@ -258,7 +258,11 @@ bool DolphinMainWindow::isFoldersPanelEnabled() const
 
 bool DolphinMainWindow::isInformationPanelEnabled() const
 {
+#ifdef HAVE_BALOO
     return actionCollection()->action(QStringLiteral("show_information_panel"))->isChecked();
+#else
+    return false;
+#endif
 }
 
 void DolphinMainWindow::openFiles(const QStringList& files, bool splitView)